1. Field of the Invention
This invention relates to a metallurgical vessel having an opening and a supporting and/or protecting flange extending around said opening.
Although the invention is applicable to all types of metallurgical installations, it will be described below, mainly in relation to installations in the steel industry, namely particularly in relation to a converter vessel for the manufacture of steel, and to a tundish for the continuous casting of steel.
2. Description of the Prior Art
A converter vessel for steel manufacture is provided with a circular flange which delimits the open mouth of the converter vessel. The vessel is lined with refractory material on its inside. The flange serves to give the converter vessel dimensional stability and to close the refractory lining at the top. A replaceable top ring, in the form of a further circular flange, is often fitted to this flange of the converter vessel, in order to protect the flange of the converter vessel from mechanical forces which arise in use e.g. during the loading of the converter with scrap, or during the scraping off of deposits. This further flange also covers and protects any exposed top surface of the refractory lining. The invention can be applied to such a top ring (or further flange) as well as to the main flange of the converter. Such structures are known to experts in this field and do not require detailed explanation.
In these flange structures, the following problems tend to occur separately and in combination:
(a) The flange of the converter vessel is deformed and shrinks during operation. In the course of time, shrinkage of 60 mm in the diameter i.e. about 1.5% has been observed; shrinkage is an ever continuing phenomenon.
(b) In the course of a campaign, the top ring begins to distort and some parts of this top ring which consists of several different parts, are lost during the campaign particularly at the location where scrap and pig iron are charged into the converter.
(c) After each campaign new parts of the top ring must be fitted to the converter.
(d) The new top ring parts must be adapted to the main flange because of the deformation and shrinkage of the main flange of the converter vessel.
(e) The repair of the top ring after each campaign involves high maintenance costs.
In the continuous casting of slabs, liquid steel is admitted to a tundish, from which the steel exits as for example two cast strands. The tundish is provided with a rectangular flange which forms the upper face of the tank which is lined inside with refractory material. The flange serves to close the refractory lining, to protect it and to retain the shape of the tank. Such a tundish is known to the experts in this field and needs no further explanation. One problem with the tundish is that the flange is sometimes deformed and/or cracked when the tundish is heated or when the tundish is used for the continuous casting of steel. Frequent repair of the flange leads to high maintenance costs.
FR-A-2085362 recognises the problem of heat stress in the flange of a converter and describes attempts to solve it by circulation of coolant. Clearly this is an elaborate and expensive measure.